Hi, Question: Describe how you would arrange for a string that is et under tension, with both ends fixed, to vibrate in its second harmonic mode. Ok, the string has a speed, v, and wavelength, w, which give it a fundamental frequency, f. If we want the second harmonic, we have to change the frequency so that a full wave fits the length of the string. So in this case we would need twice the frequency, or half the wavelength. I think this is how you would do it but, as you can see, I am still a bit confused. How could I formally answer this question? Thanks, Peter G.